Method of forming composite boards



March 21, 1944. R T BOWLING 2,344,488

METHOD OF FORMING COMPOSITE BOARDS Filed Jan. 15, 1941 2 Sheets-Sheet lR08 ERT T. BQWLING |NvENToR ATTORNEY March 2l, 1944. R; T BOWLlNG2,344,488

METHOD 0F FORMIYNG COMPOSITL] BOARDS.

l Filed Jan. 13, 1941 2 sheets-sheet 2 ROBERT 1*. eowLms INVENTORATTORNEY composite board.

labutting relation.

A further objectv of my invention has been to Patented Mar. 2l, 1944UNITED STATES PATENT oFFlcE METHOD OF FORMING COMPOSITE BOARDS Robert T.Bowling, Lewiston, Idaho, assigner to Potlatch Forests, Inc., Lewiston,Idaho Application January 13, 1941, Serial No. 374.281

l Claims. (Cl. 1445-309) This invention relates to an improved method offorming. composite boards. wherein a plurality of boards are joinedtogether side by side to form a unitary panel.

In lumbering operations, and in the subsequent milling of the lumber.there often occursy the production of lumber that is narrow inw'ldth orshort in length and yet is relatively free from knots, blemishes orother value detracting conditions and would be suitable for many uses inlarger sizes. Because of the narrowness or sh0rtness boards of thisnature do notcommand a market price commensurate with the graincondition or other factors that they possess. The market value for lulldimension boards of the same degree of clearness or of grain conditionis often several times greater than the shorter or narrower boards cancommand. 'I'his presents the problem of effecting a conversion of suchboards into desirable sizes whereby the value of such board may beincreased.

It has, therefore, been a prime object of my invention to provide aneilicient speedy method of joining short or narrow boards to form alarger Another object of my invention has .been to provide a method ofjoining short or narrow boards to form a. composite board having athickness equal to any one board while in width or length, as the casemay be, the composite board will comprise a plurality of boards joinedin edgewise provide a methodoi forming composite boards.

wherein the components are of standard shapes 't and dimensions thatresult from a conventional wood milling operation and made availablewithout the necessity of sracial mill practices.

Still another object of my invention has been to incorporate in mymethod the use oi high speed glue applicators of heat and pressure sothat my method may be practiced with rapidity and thus produce a highrate of production. at a miniminn cost.

Other objects and advantages of my invention will be apparent from thefollowing. description wherein I have set forth the various steps of mymethod. While certain specic details of machinery may be described, itis to be understood that that description is solely for the purpose ofillustration and is not to be construed as a limita..

tion of the invention beyond those that may appear in the subjoinedclaims.

In the drawings- Figure l is an end view of a set or quantity ofprepared boards that are to be joined to form a composite boardaccording to the principles of my invention,

"Figure 2 illustrates schematically the step o! applying a liquid oriiuid adhesive to an edge of a prepared board,

Figure 3 illustrates a set comprising a plurality of adhesive-preparedboards aligned and ready 4for joining,

Figure 4 illustrates a preheating step employed in my method preliminaryto joining the indifvidual members to form a composite board,

Figure 5 is an end view that shows the eil'ect of preheating a board,

Figure 6 illustrates the step in my method wherein the individualmembers are aligned and arranged according to a pattern for the iinaljoinder step,

Figure 7 shows the manner in which pressure and heat is applied toboards arranged as shown in Figure 6 to eil'ect the ultimate joinder ofa unitary composite board, and

Figure 8` is a perspective view of a ilnished composite board i'ormedaccording to my novel method.

AnI initial step in preparing for the production of a composite board,of the nature shown in Figure 8. is to cut and `prepare a plurality orset of boards referred to by numerals of reference Il, I I, I2, I3 andIl. The edges are cut and planed, preferably to present a true, smoothface at right angles to the cross axis of the boards. In certaininstances these edges may be beveled or angularly cut with reference tothe boards lateral axis. In that event the boards of a group to bejoined will all be provided with matching edges. In the iinishedcomposite board according to this description the set of boards l0, II,I2, I3 and I4 will be joined in the order indicated in Figure 1 in anedge-abutting or side-by-side manner.

A subsequent step in my method is the application o! an adhesive,preferably a iluid glue to the edge of certain boards. A verysatisfactory application of glue may be accomplished by the apparatusindicated in Figure 2. An edge I0 of each board In, II, I2 andy I3 iscaused to pass over a roller device comprising a plurality of discs I'Iwhich are mounted on shaft I8 for rotation. LA vat i9 supports the shaftI8 in journals 10, 2li and encloses a quantity of fluid glue 2|. Thelower edges of the discs I1 are partially immersed inthe glue. As aboard is passed over the discs,

they will be caused to roll and pick up glue from the vat and to depositit on the edge i6 of the board. In this example, three parallel leads orstrings of glue 23, 24 and 25 will bedeposited although more or less maybe used as occasion will require.

I have found that my method may be veryand the edges I6 of board I3 willcarry the glue or other adhesive for the ioint between boards I3 and I4.v

Another step in my method comprises the heating of an edge of certainboards of a set. In the final joinder of paired boards, an adhesiveproerations.

vided edge is preferably caused to abut against a preheated edge tofacilitate the action of the adhesive. A suitable apparatus forpreheating board edges is one which I have devised which is essentiallya table comprising spaced apart table-top sections 28 which providelongitudinal slots 29.v Aligned with and below the slots 29 are heaterblocks 30 having heater elements 3| disposed in the upper faces of theblocks. In composite boards wherein ilve units arev joined only boardsII, I2, I3, and Il need have an edge as 32 heated since there are onlyfour joints. During the gluing operation the board I0 of the set may bedisposed on the table surface since it is advisable to initially assortand arrange the units ultimately to be joined and then to process themas a group or set throughout the various steps of my method. l

The edges 32 of the boards will be permitted to rest adjacent the heaterelements long enough for the wood to absorb heat for some distance infrom the edge as I have indicated in Figures 5 and 6."

In the final stages of my method the boards i' a set are subjected toside pressure and simultaneously to top and bottom pressure along theedges oi' the boards close to the joints. Side pressure rails 34 and 35are caused to engage the outer edge of boards II) and Il and to closeagainst each other and to bring the abutting edges of individual boardsof the set together. Simultaneously the boards may be pressed on eachside, top and bottom, by upper pressure bars I6 and lower pressure bars31. 'I'he pressure applied by the rails 3l and 35 and by bars 36 8nd 31in c108- ing is indicated by the arrows in Figure 7.

, boards at the joints.

When the boards are closed together and preheated boards are used, theheated edges l2 ra.- diate heat upon the adhesive applied to edges IlIand tend to make the board on which it is supplied more receptive togluing. In this way heat is applied in the center of the loint andfacilitates and speeds up the gluing operation. The heat also preparesthe adhesive for rapid and eiective spreading in the Joint.

I also prefer to provide the pressure bars Il and 31 with heaterelements It similar to eiements 3i in blocks III. In that arrangement,simultaneous with the application of top and bottom pressure to theboards of a set, heat is applied to the joints to assist in the gluingop- 'I'he elements Il may be placed in grooves in thenresslng faces ofbars 38 and l1 in such a manner as will not mar the board faces orinterfere with the pressure application.

In the practice of my method I have been able to produce'compositeboards at 90 second intervals. A preferable characteristic of a suitableglue is that it be capable of rapidly drying or setting in the Iiointbetween boards. Thus, when an adhesive-carrying board is presented toanother board at a Joint and the two pressed together, the adhesive willreadily now and set in the joint.

Having thus described my invention, I claim;

1. 'I'he method of making a composite board which includes applying anadhesive to a lateral edge of one board, preheating a lateral edge ofanother board, assembling these boards with their treated edges incontact to form a joint `supporting the boards in horizontal position,ap-

plying lateral pressure against the assembled boards, simultaneouslyapplying vertical pressure on the tops of the boards at theirjoint-edges, and confining and applying heat only to the upper and lowerfaces of the boards at the Joint.

2. 'I'he method of making a composite board which consists in applyingadhesive to the inner lateral edge of one outside board, preheating theinner lateral edge of the other outside board, successively applying anadhesive to one lateral edge and preheating the opposite edge of each ofthe intermediate boards, assembling the boards and supporting them inhorizontal position to form joints between abutting treated edges,applying lateral pressure against the assembled boards, simultaneouslyapplyingvertical pressure against the boards and Separately confiningand applying heat only at the upper and lower faces of the aonna'r '1'.BOWLING.

